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C l e a r l y   b e t t e r   s o u n d

E&OE

Issue_1.0

The power amplifiers shall be available in four channel and eight channel 

versions. Either version shall be capable of driving 50 W per channel 

into a 4 ohm load when all channels are driven simultaneously.

The amplifiers’ front panels shall incorporate an AC power switch, 
an LED indicating POWER ON, and LEDs indicating Signal Present, 

Peak Level and Protect status for each channel. The Signal Present 
LEDs shall illuminate when the output level is 22 dB below the rated 
output. The Peak LEDs shall illuminate at the onset of signal clipping. 

The Protect LEDs shall indicate activation of the channel protection 
circuitry.

The  amplifiers  shall  be  provided  with  one  input  per  channel  and 
be  able  to  operate  in  the  following  configurations  as  a  minimum: 

all  channels  independent,  one  input  feeding  all  channels  or  two 
inputs feeding the amplifier channels in pairs for stereo operation. 

Signal level adjustment will be provided for each channel via a rear 

panel  control  permitting  a  range  of  operation  from  not  less  than 
90  dB  attenuation  (min.)  to  unity  gain  (max.). The  inputs  shall  be 

electronically balanced and capable of operating with both balanced 
and  unbalanced  sources. The  input  impedance  shall  be  10  kohms 

(balanced). The input connectors shall be of Euroblock type. It shall 
be  possible  to enable  a high-pass  3rd-order  filter  with  a  turnover 
frequency of 65 Hz independently in each amplifier channel. 

Each  channel  shall  deliver  its  rated  power  from  an  input  signal 

of  0  dBu  with  input  level  controls  set  at  maximum.  Output  mute 
protection on power-up and thermal protection shall be provided. 
The  amplifiers  will  also  be  protected  against  short-circuits  at  the 

output, and excessive combination of output voltage and current. The 

amplifiers’ outputs shall be on Euroblock connectors.

A range of optional, single-channel transformer modules, and suitable 

rackmounting  housings,  shall  be  available  to  permit  the  amplifiers 
to drive 100 V-line and 70 V-line loudspeaker systems. It shall also 

be  possible  to  adapt  the  four  channel  amplifier  version  for  direct 
connection to 100 V-line and 70 V-line systems by the addition of an 
internally-fitted four-channel transformer module.

An optional remote control shall be available for any or all amplifier 

channels, to allow adjustment of channel gain. The remote control 

connector shall be of Euroblock type. It shall also be possible to fit 
optional EQ cards to any or all channels to suit a range of current, 

popular loudspeaker types.

The amplifier shall be built in a steel chassis suitable for mounting in 

a standard 19” equipment rack, and occupy two rack spaces. Variable 
speed forced-air cooling shall be employed.

The amplifier shall be available in versions operating on either 230 V 

or 115 V AC mains, the intended mains voltage to be specified by the 
user at the time of order.
 
The power amplifiers shall be the Cloud CX-A450 (four channels) 
and CX-A850 (eight channels).

Architect’s and Engineer’s Specification

Summary of Contents for CX-A450

Page 1: ...lso available To prevent LF transformer saturation in 100V 70V line systems a 65 Hz high pass filter may be enabled for each channel individually by internal jumper Other standard options are Cloud RL 1 remote volume control plates the VCA 5 single channel VCA card required for level control by RL 1 and EQ cards to suit various makes and models of loudspeakers Remote level control or speaker EQ ma...

Page 2: ...ion Pairs of channels may be operated in Bridge Mode Per channel front panel LEDs for signal presence peak level and protection status Balanced line level inputs with gain trim Rear panel switches to configure for multichannel stereo or mono operation Optional internal 4 channel 100 V 70 V transformer module CX A450 only Optional externally mountable 100 V 70 V transformers per channel Optional re...

Page 3: ...e r s o u n d Input Routing The input routing switches of the CX A450 and CX A850 permit various permutations of mono stereo and multi channel operation without any external parallel wiring Some possibilities are shown below ...

Page 4: ...d to various zones parts of a building They are equally suitable in a situation where a common audio source needs to be reproduced at different levels in various zones The flexibility of the amplifiers input routing makes it possible to handle a mixture of mono and stereo sources without complex wiring In many applications the power amplifiers will be used in combination with a Cloud Zoner to perm...

Page 5: ...p Trace Line Style Thick Data Axis Comment 1 1 Red Solid 1 Anlr Bandpass Left CH2 to CH1 100 0 80 60 40 20 d B r 20 20k 50 100 200 500 1k 2k 5k 10k Hz T T Audio Precision 05 31 11 13 23 50 CX A850 Crosstalk Color Sweep Trace Line Style Thick Data Axis Comment 1 1 Red Solid 1 Anlr Bandpass Left 100 0 80 60 40 20 d B r 20 20k 50 100 200 500 1k 2k 5k 10k Hz T Audio Precision 05 31 11 13 11 59 CX A450...

Page 6: ...stalk 70 dB rel rated output into 4 ohms 10 kHz 82 dB rel rated output into 4 ohms 10 kHz VCA module THD N 0 03 1 kHz 22 Hz 80 kHz BW Inputs Type connectors Electronically balanced 3 pin 3 5 mm pitch screw terminal connectors Sensitivity 0 dBu 0 775Vrms Input Impedance 10 kohms balanced General Output Connectors lo Z 2 pin 5 mm pitch screw terminal connectors Output Connectors 100 70 V Screw termi...

Page 7: ...ency of 65 Hz independently in each amplifier channel Each channel shall deliver its rated power from an input signal of 0 dBu with input level controls set at maximum Output mute protection on power up and thermal protection shall be provided The amplifiers will also be protected against short circuits at the output and excessive combination of output voltage and current The amplifiers outputs sh...

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